This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the present invention. The following discussion is intended to provide information to facilitate a better understanding of the present invention. Accordingly, it should be understood that statements in the following discussion are to be read in this light, and not as admissions of prior art.
With recent advances in thin-film transistors and organic/inorganic semiconductor inks, printed electronic techniques have seen increased development and usage. It is now possible to create transistors, light emitting diodes and flexible circuits using these printed electronic techniques, such as screen-printing, ink-jet and gravure. Printed electronic techniques provide the potential for low cost, lightweight and flexible electronics.
This invention formulates a means to concurrently utilize two printed electronic components, a printed sensing element 203 and a printed diode 208, in order to provide current flow control to a mechanical force sensor or sensors, and is manufactured using printed electronic techniques that allow for thin, flexible, low cost production.
Different embodiments of the printed sensing element 203 have been in use for several decades. A printed sensing element 203 with force sensitive resistive material 24, for instance, has been in use since the 1970s. An issue with using a PSE 203 in a larger circuit or using several PSE 203 connected in a network is that current can flow in both directions through a sensing element, often creating alternate circuits that create false positive 224 or drain 223 cross-talk 222. In these situations, the crosstalk causes variability to the values of the signal being read from similar mechanical forces being applied to the PSE 203. To address this, the PSE 203 either had to be isolated into single element circuits or computer algorithms were used to compensate for the errors. A non-printed diode could be placed on a printed circuit board 8 before each PSE 203 but this would requires networks of PSE 203 to return to the circuit board between each PSE 203 and would be impractical with an active sensing array 20 of PSE 203.
In prior art, a two-dimensional grid of PSE 203 forms an active sensing array of elements (ASA) 20. Tekscan, for instance, has created an ASA 20 using FSR material 24 that provides a time-varying pressure image.
Printed diodes are a relatively recent development, with continued growth in its commercial use over the past five years (2007-2012). The primary uses in the industry have been for organic light-emitting diode (OLED) displays and for flexible electronics. Breakthroughs in organic and inorganic semiconductors have made it possible to print electronic circuits on flexible substrates using printed electronic techniques.
This invention solves the cross talk 222 of the PSE 203 by depositing a printed diode 208 in contact with each PSE 203 to form a printed diode-sensing element (PDSE) 211. By using printed electronic techniques for the sensing element and the diode, one or more PDSE can be made that control the flow of current and can be made on a thin, low-cost, flexible substrate.